Squamous cell carcinoma (SCC) of the vulva, although uncommon, is a significant health problem in the United States, especially for minority women. Recent studies correlating pathologic and virologic features have suggested that SCC of the vulva comprises two etiologically distinct entities: human papillomavirus (HPV)-related basaloid and warty SCC occurring mostly in younger women, and HPV-unrelated, typical SCC occurring mostly in older women. The objective of this proposal is to test the validity of this hypothesis and to characterize the histologic subtypes. Archival and fresh tissue specimens of vulvar cancers collected from Johns Hopkins Hospital and from collaborating investigators (Dr. Richard Zaino, Hershey Medical Center; Dr. Edward Wilkinson, University of Florida; and Dr. Louise Brinton, National Cancer Institute) will be examined to determine if they can be reproducible divided into histologic subtypes (typical SCC vs. basaloid and warty SCC) and if the histologic subtypes correlate with the presence of HPVs (warty and basaloid SCC) or the absence of HPVs (typical SCC). The presence, types and tissue localization of the HPV genomes will be determined by polymerase chain reaction and in situ hybridization. Patients with HPV-negative and HPV-positive vulvar SCC will be compared with respect to tumor morphology, adjacent tissue morphology, age at diagnosis and other characteristics. Patients with HPV-related and HPV-unrelated SCC will be compared for the clinico-pathologic characteristics of the tumors and for survival. The outcome of putative precursor lesions will be studied in a group of women at Johns Hopkins who have this diagnosis and have been monitored conservatively for over 20 years. Pathological tissues from cases of a recently completed case- control study of vulvar SCC will be characterized virologically and reclassified histologically. The epidemiologic data will then be re- examined to determine if the two subtypes have different risk factors. HPV-related and HPV-unrelated carcinomas and their respective putative precursors will be compared for p53 gene mutations and for alterations of other tumor suppressor genes to examine precursor-carcinoma relationships and to determine if the mutational events in the two carcinoma subtypes are similar or different. Recognition and characterization of two etiologically and pathogenetically distinct processes, both of which lead to vulvar SCC, may lead to clarification of risk factors for the disease and improvement of clinical management.